Over the last several decades spectroelectrochemistry has gained considerable importance as an analytical technique for measuring, simultaneously the redox and spectral properties of inorganic, organic, and biological species. Spectroelectrochemistry can be implemented in cells that are characterized by either semi-infinite linear diffusion (SILD) in a bulk solution or by thin layer (TL) cells in which complete electrolysis is rapidly achieved in a thin layer of solution. The spectroscopic methods that have been used rely on light propagation through the sample based on transmission, specular reflection or internal reflection. In transmission spectroscopy, a light beam is passed through an optically transparent electrode and the sample. In specular reflection spectroscopy the light is passed through the sample, reflected off the electrode surface and then back through the sample. In internal reflection spectroscopy the light is directed into a wave guide at an angle less than the critical angle so that it is internally reflected. At each reflection point an evanescent electromagnetic wave interacts with the sample and changes in the spectra can be measured.
Spectroelectrochemistry has been used for a wide range of applications. In spite of the broad scope of both SILD and TL spectroelectrochemistry, wide applicability of the technique is limited by cell designs that are complicated to construct and use and that require relatively large sample sizes—on the order of milliliters.
What is needed is an electrochemical technique keeping the total sample volume as small as possible to obtain electrochemical information as half-wave potentials and diffusion coefficients. What is also needed is a technique of electrochemical detection with simultaneous spectroscopic detection in order to acquire spectroelectrochemical data in an easy and rapid way. What is further needed is a method and apparatus for lowering the distance between the working electrode and the transparent surface that contains the analyte solution so as to create a thin-layer spectroelectrochemistry environment. This technique and environment will allow for acquisition of spectroelectrochemical data in an easy, rapid and economic way and determine redox potentials.